This may be something that happens. At the time of the Cube, Apple didn't have the market interests it has now. Which is PC users who want to come on over but want what they had on the other side, expandibility and options.
I agree that the iMac doesn't fit this market. However it does fit the market Apple intends it for. When most people buy a computer, they get a monitor with it. So there are not buying it "headless" as one would call it. Apple simplifies that process by putting it into an all-in-one package.
Everyone saying that you have to "throw away a display" is just ridiculous. Most people who have iMacs keep them for years. Not one or two either. I am going to digress to make another point.
This is where the argument of price comes in. People will say "Apple computers cost too much", in comparison to a bargain basement $299 Dell with a CRT, yeah it is. However, when you buy an Apple you are getting the fastest and best tech out there, so that computer lasts you many years to come.
Anyhow, I don't really think Apple is going to give into the pressures of this new market. As there really isn't a place for it. I guess they could bring it back as the Mac Cube, but after the failure that the Cube was I don't see that happening.
Apple is covering what it feels it market is. When they feel they should step into another sector they will. I don't think posting here is going to help you out at all.